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  Subjects -> CHEMISTRY (Total: 773 journals)
    - ANALYTICAL CHEMISTRY (45 journals)
    - CHEMISTRY (537 journals)
    - CRYSTALLOGRAPHY (22 journals)
    - ELECTROCHEMISTRY (24 journals)
    - INORGANIC CHEMISTRY (40 journals)
    - ORGANIC CHEMISTRY (41 journals)
    - PHYSICAL CHEMISTRY (64 journals)

ANALYTICAL CHEMISTRY (45 journals)

Accounts of Chemical Research     Full-text available via subscription   (Followers: 217)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 9)
Acta Analytica     Hybrid Journal   (Followers: 6)
Advances in Analytical Chemistry     Open Access   (Followers: 19)
American Journal of Analytical Chemistry     Open Access   (Followers: 26)
Analytica Chimica Acta     Hybrid Journal   (Followers: 32)
Analytical and Bioanalytical Chemistry     Hybrid Journal   (Followers: 26)
Analytical Chemistry     Full-text available via subscription   (Followers: 310)
Analytical Chemistry Insights     Open Access   (Followers: 17)
Analytical Letters     Hybrid Journal   (Followers: 9)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 10)
Annual Review of Analytical Chemistry     Full-text available via subscription   (Followers: 9)
Chinese Journal of Analytical Chemistry     Full-text available via subscription   (Followers: 3)
Combinatorial Chemistry - an Online Journal     Open Access   (Followers: 2)
Comprehensive Analytical Chemistry     Full-text available via subscription   (Followers: 5)
Critical Reviews in Analytical Chemistry     Hybrid Journal   (Followers: 25)
Current Analytical Chemistry     Hybrid Journal   (Followers: 6)
Drug Testing and Analysis     Hybrid Journal   (Followers: 4)
Electroanalysis     Hybrid Journal   (Followers: 3)
Field Analytical Chemistry and Technology     Hybrid Journal   (Followers: 5)
Handbook of Analytical Separations     Full-text available via subscription   (Followers: 1)
Handbook of Thermal Analysis and Calorimetry     Full-text available via subscription  
International Journal of Analytical Chemistry     Open Access   (Followers: 20)
International Journal of Chemical and Analytical Science     Full-text available via subscription   (Followers: 3)
International Journal of Environmental Analytical Chemistry     Hybrid Journal   (Followers: 5)
International Journal of Polymer Analysis and Characterization     Hybrid Journal   (Followers: 4)
ISRN Analytical Chemistry     Open Access   (Followers: 16)
ISRN Chromatography     Open Access   (Followers: 2)
Journal of Analytical & Bioanalytical Techniques     Open Access   (Followers: 5)
Journal of Analytical Atomic Spectrometry     Full-text available via subscription   (Followers: 8)
Journal of Analytical Chemistry     Hybrid Journal   (Followers: 15)
Journal of Electroanalytical Chemistry     Hybrid Journal   (Followers: 4)
Journal of Essential Oil Research     Hybrid Journal   (Followers: 2)
Journal of Radioanalytical and Nuclear Chemistry     Hybrid Journal   (Followers: 3)
Journal of Thermal Analysis and Calorimetry     Hybrid Journal   (Followers: 18)
Main Group Metal Chemistry     Full-text available via subscription   (Followers: 1)
Microchemical Journal     Hybrid Journal   (Followers: 3)
Phytochemical Analysis     Hybrid Journal   (Followers: 1)
Polish Journal of Chemical Technology     Open Access   (Followers: 2)
Reviews in Analytical Chemistry     Full-text available via subscription   (Followers: 8)
Surface and Interface Analysis     Hybrid Journal   (Followers: 13)
Techniques and Instrumentation in Analytical Chemistry     Full-text available via subscription   (Followers: 7)
TrAC Trends in Analytical Chemistry     Full-text available via subscription   (Followers: 21)
Trends in Environmental Analytical Chemistry     Hybrid Journal   (Followers: 1)
Vibrational Spectroscopy     Hybrid Journal   (Followers: 8)
Journal Cover Journal of Analytical Chemistry
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   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 1608-3199 - ISSN (Online) 1061-9348
     Published by Springer-Verlag Homepage  [2209 journals]   [SJR: 0.322]   [H-I: 17]
  • Extraction-spectrophotometric determination of mefenamic acid in
           pharmaceutical preparations
    • Abstract: Abstract The optimal conditions of the formation and extraction of mefenamic acid ion associates with the astrafloxin polymethine dye are studied. The extraction of ion associates with isooctane-dichloroethane mixtures attains a maximum at pH 9–11 and dye concentration of (5–7) × 10−5 M. The Beer law is fulfilled in the range 2.0–21.0 μg/mL; the detection limit for mefenamic acid is 0.72 μg/mL. A method is developed for the extraction-spectrophotometric determination of mefenamic acid in pharmaceutical preparations.
      PubDate: 2014-10-01
       
  • Electrophoretic and gas-chromatographic analysis of an Afobazol
           pharmaceutical preparation
    • Abstract: Abstract Procedures for determining 5-ethoxy-2-[2-(morpholino)ethylthio]benzimidazole dihydrochloride, an active component of the Afobazol medicinal preparation, and its potential impurities, 5-ethoxybenzimidazol-2-thione and N-(2-chloroethyl)morpholine hydrochloride by capillary zone electrophoresis in the range 2.0 × 10−5 to 2.0 × 10−3 M and ligand-exchange capillary electrophoresis in the range 1.0 × 10−5 to 5.0 × 10−3 M are developed. The optimum conditions for the separation and determination of these analytes using a quartz capillary tube are found. The reliability of the results obtained by capillary electrophoresis was confirmed by gas chromatography with a mass-selective detector.
      PubDate: 2014-10-01
       
  • Liquid chromatography of some steroid hormones in aqueous-organic,
           micellar, and cyclodextrin mobile phases
    • Abstract: Abstract The retention of hydrocortisone, progesterone, dexamethasone, and prednisolone is studied by HPLC and thin-layer chromatography using aqueous-organic, micellar, and cyclodextrin mobile phases. It is demonstrated that micellar and cyclodextrin mobile phases improve the efficiency and selectivity of the chromatographic separation of the indicated hormones compared to aqueous-organic eluents. By comparing the numbers of theoretical plates, the heights equivalent to a theoretical plate, and resolution it was found that micellar mobile phases are more efficient than cyclodextrin ones and can be used for work with Sorbfil plates.
      PubDate: 2014-10-01
       
  • Simultaneous spectrophotometric determination of pyrantel pamoate and
           febantel in pharmaceutical preparations using partial least-squares
           regression
    • Abstract: Abstract The multivariate spectroscopic determination of the combination of pyrantel pamoate (PP) and febantel (FB) in pharmaceutical preparations was carried out by partial least-squares regression. The UV absorbance spectra of standard mixtures of PP and FB were measured at concentrations ranging from 5.76–11.52 and 6–12 μg/mL, respectively, in a diluent solution of methanol and acetonitrile. The best model was selected with variable selection (280–320, 380–400 nm), 2 latent variables and mean centered. External validation was performed using 13 different mixtures, which provided prediction errors lower than 1%. The method was validated in accordance with international and Brazilian guidelines. This method was successfully employed to quantify the drug content in two different pharmaceutical formulations (solid — capsules, liquid — oral suspensions) with good prediction capacity. Furthermore, its advantages include the use of simple and accessible reagents and equipment, and a low operating cost.
      PubDate: 2014-10-01
       
  • Evaluation of the antioxidant properties of spices by cyclic voltammetry
    • Abstract: Abstract The individual antioxidants of spices (gallic and rosmarinic acids, capsaicin, thymol, and eugenol) are irreversibly oxidized at 0.88–1.25 V at a glassy carbon electrode in 0.1 M LiClO4 solution in ethanol. Corresponding electrode reactions are proposed. A linear dependence of the oxidation step area on the concentration is observed for all the analytes. The detection limits and the lower limits of quantification vary from 0.57–12 and 1.8–40 μM, respectively. Distinct steps and peaks of oxidation are observed on cyclic voltammograms of the methanolic extracts of spices; the potentials and areas of these peaks depend on the type of spice. The contribution of individual antioxidants to integral responses of spice extracts is evaluated. A method is developed for the voltammetric evaluation of the antioxidant capacity (AOC) of spices based on the oxidation of their antioxidants. The total area of the oxidation steps was selected as a parameter characterizing the antioxidant properties. The AOC of spices was expressed as a weight of gallic acid in milligrams per 1 g of a dry spice. Seventeen different spices were tested. The AOC decreases in the series of clove > juniper berries > nutmeg > cinnamon > rosemary > anise ≥ oregano > black pepper ≥ ginger ≥ basil > turmeric > red pepper ≈ bay leaf ≥ coriander ≈ red sweet pepper > cumin > caraway. A correlation between the AOC obtained by voltammetry and the total AOC, ferric reducing power, antiradical activity, and total content of phenolic compounds and these parameters with each other is found; the correlation coefficients vary in the range 0.8886–0.9615.
      PubDate: 2014-10-01
       
  • Determination of bismuth in pharmaceutical products by resonance light
           scattering using quaternary ammonium salts as molecular probe
    • Abstract: Abstract Resonance light scattering (RLS) of bismuth-iodide-quaternary ammonium salts and their analytical application have been studied. Bismuth can react with a large excess of I− to form [BiI4]− in the presence of Tween-20; [BiI4]− further reacts with quaternary ammonium salts such as tetramethyl ammonium bromide (TMAB), tetrapropyl ammonium bromide (TPAB) and tetrabutyl ammonium bromide (TBAB) to form an ion-association compound. Moreover, the characteristics of RLS spectra of the complexes, the optimum conditions and the influencing factors have been investigated. The method has been applied to determine Bi(III) in pharmaceutical products with satisfactory results which are in agreement with that of atomic absorbance spectrometry (AAS).
      PubDate: 2014-10-01
       
  • Study of forced degradation behavior of idrocilamide and development of
           stability indicating LC method
    • Abstract: Abstract The objective of this study was to report the stability profile of novel muscle relaxant drug idrocilamide (Idr) based on information obtained from forced degradation studies. The drug was subjected to acidic (1 M HCl) and alkaline (1 M NaOH) hydrolysis and oxidative decomposition (50% H2O2). The products formed under different stress conditions were investigated by LC. The LC method was fine tuned using the samples generated from forced degradation studies. Satisfactory resolution between peaks with the shortest possible analysis time was achieved on C18 5 μm column (Luna, Phenomenex, USA), with mobile phase methanol-acetonitrile-water-glacial acetic acid (25: 30: 44: 1, v: v: v: v), pumped at 1 mL/min flow rate. Quantification was achieved at 280 nm based on peak area, using DAD detector. The proposed LC method was utilized to investigate the accelerated oxidative degradation of Idr. Besides, Idr’s degradants were identified using IR and MS, and the possible degradation pathway was outlined. The proposed method was validated, and the forced degradation studies proved the stability indicating power of the method. The method was also applied to analyze commercial samples.
      PubDate: 2014-10-01
       
  • Analytical methods for studying the stability of pharmaceutical
           compositions and the compatibility of their components
    • Abstract: Abstract A review of publications on studying the stability of pharmaceutical preparations and interactions of their components is presented. Volumetric and physical factors activating decomposition processes are considered. Specific features of mixture analysis by optical, chromatographic, and thermoanalytical methods are discussed together with the advantages and disadvantages of methods and possibilities of their combination.
      PubDate: 2014-10-01
       
  • Sensitive and selective determination of tolterodine tartrate and its
           electrochemical investigation on solid carbon based electrodes
    • Abstract: Abstract Tolterodine tartrate, a muscarinic receptor antagonist, was oxidized in various buffer media with different pH values using cyclic, differential pulse, and square wave voltammetric techniques on glassy carbon and boron-doped diamond electrodes. Two irreversible anodic peaks were obtained. The oxidation process of tolterodine tartrate was diffusion controlled depending on pH for both electrodes. A detailed oxidation mechanism was proposed and discussed. The dependences of the peak current and peak potentials on pH, concentration, nature of the buffer, and scan rate were investigated. A linear response between the peak current and the tolterodine tartrate concentration was obtained using differential pulse and square wave voltammetric techniques in the range of 0.4–8.0 μM for the peak at lower potential in acetate buffer at pH 5.7 and 0.4–40.0 μM for the peak at higher potential in 0.1 M H2SO4 on glassy carbon electrode and in the range of 0.4–40.0 μM in Britton-Robinson buffer at pH 11.0 on boron-doped diamond electrode. Limit of detection values varied between 0.04 and 0.13 μM for both techniques and electrodes. The repeatability, reproducibility, precision, and accuracy of the proposed methods were investigated. The recovery studies were also achieved to check selectivity, precision, and accuracy of the methods. The proposed methods were successfully applied to determine tolterodine tartrate from pharmaceutical dosage forms without any interference from inactive excipients.
      PubDate: 2014-10-01
       
  • Electrochemical determination of acetaminophen in the presence of
           propranolol using an electrode modified with a Schiff base from
           2-hydroxy-1-naphthaldehyde and ethylenediamine and multi-walled carbon
           nanotubes
    • Abstract: Abstract A carbon paste electrode, modified with N,N′-bis-(2-hydroxy-1-naphthalidene)ethylenediamine and multi-walled carbon nanotubes (HNED-MWCNPE), was used for the determination of acetaminophen (ACOP) and propranolol (PP). Cyclic voltammetry (CV), chronocoulometry, chronoamperometry and differential pulse voltammetry (DPV) techniques were employed to study electro-oxidation of ACOP. The results revealed that the modified electrode showed an electrocatalytic activity toward the anodic oxidation of acetaminophen by a marked enhancement in the current response in buffered solution at pH 8.0. Some kinetic parameters such as the electron transfer coefficient (α) were also determined for the ACOP oxidation. The linear concentration range of 1 × 10−3−1 × 10−6 M with a detection limit of 4.6 × 10−8 M (n = 16) for ACOP was obtained using DPV (pH 8.0). The modified electrode shows good sensitivity, selectivity and stability. The prepared electrode was also applied for the determination of ACOP in human blood serum.
      PubDate: 2014-10-01
       
  • A new sensitive spectrophotometric determination of sodium
           2-mercaptoethanesulfonate using leuco xylene cyanol FF
    • Abstract: Abstract A simple and accurate spectrophotometric method for determination of sodium 2-mercaptoethanesulfonate (MESNa) with leuco xylene cyanol FF (LXCFF) has been developed. The proposed method is based on the reaction of MESNa with potassium iodate(V) in acidic medium to liberate iodine, which oxidizes leuco xylene cyanol FF to its blue form xylene cyanol FF. The xylene cyanol FF dye formed shows maximum and stable absorbance at pH 4.1–4.2. Absorbance of the obtained colored products was measured at 613 nm. The molar absorptivity, limit of detection and limit of determination of the method were found to be 3.64 × 104 L/mol cm, 0.29 and 0.33 μg/mL, respectively. The colour system obeys Beer’s laws in the range 0.4–4.0 μg/mL of MESNa. All the variables were studied in order to optimize the reaction conditions. The procedure was used for determination of MESNa in pharmaceutical preparations. Reliability of determination was confirmed applying standard iodometric method, recommended by European and Polish Pharmacopoeia.
      PubDate: 2014-10-01
       
  • Photometric determination of sulfanilic amide derivatives in drug
           formulaions and blood plasma
    • Abstract: Abstract 2,3,5,6-Tetrachloro-p-benzoquinone (TCPBQ) generated in the oxidation of sulfanilic acid amide derivatives was found to form a colored product with sodium diethyldithiocarbamate (DEDTC). The optimal conditions for the formation of this compound are determined. A possibility of using the oxidation reaction to TCPBQ followed by interaction with DEDTC as a versatile scheme for the photometric determination of sulfanilic amide derivatives in drug formulations and blood plasma was demonstrated.
      PubDate: 2014-10-01
       
  • Quantitative determination of the average molecular weights of dextrans by
           diffusion ordered NMR spectroscopy
    • Abstract: Abstract Diffusion ordered NMR (DOSY) was applied to the determination of the average molecular weights of polymers based on the dependence of the measured self-diffusion coefficient D on the corresponding weights of a number of polymers of the same type. As a rule, a calibration function is plotted by varying DOSY experimental parameters for each particular test sample; however, this approach is inapplicable to the development of a standard procedure for the quantitative assessment of the molecular weights of dextrans. In this article, an optimization method is considered to ensure high resolution in terms of the values of D for dextrans without varying experimental conditions; this method makes it possible to evaluate the average molecular weights of dextrans with a high accuracy over a wide range of their values.
      PubDate: 2014-10-01
       
  • Simultaneous determination and validation of some binary mixtures of
           antihypertensive drugs using ratio derivative spectrophotometric method
    • Abstract: Abstract Ratio derivative spectrophotometric technique is presented for the rapid, accurate and precise simultaneous determination of olmesartan medoxomil (OLM), hydrochlorothiazide (HCT), and zofenopril (ZOF) as well as HCT binary mixtures in their dosage forms. First derivative of the ratio spectra (DD1) by measurements using different amplitudes was used and calibration graphs were established for 0.5–12 mg/mL HCT and 0.5–20 mg/mL OLM and ZOF. This method depends on first derivative of the ratio spectra by division of the absorption spectrum of the binary mixture by a standard spectrum of one of the components and then calculating the first derivative of the ratio spectrum. The first derivative of the ratio amplitudes at 250.4 and 291.5 nm for OLM, 250.4 and 298.1 nm for ZOF and 231.8, 332.2, 232.3 and 280.4 nm for HCT were selected for the determination. The proposed methods were successfully applied for determining of both drug combinations (ZOF-HCT and OLM-HCT) in their synthetic mixtures and in pharmaceutical dosage forms. The described procedures are extensively validated, non-destructive and do not require any separation steps.
      PubDate: 2014-10-01
       
  • Extraction and HPLC determination of the ascorbic acid content of three
           indigenous spice plants
    • Abstract: Abstract Three sample preparation methods (wet grinding followed by centrifugation, ultrasonic-assisted extraction and microwave-assisted solvent extraction) for extracting ascorbic acid (AA) from parsley, dill and celery were evaluated. AA was extracted into 8% aqueous solutions of acetic acid, metaphosphoric acid and trichloroacetic acid, respectively. An efficient and precise high-performance liquid chromatography method was used for detecting AA. The best extraction technique was ultrasonic-assisted extraction, and acetic acid was the best extractant. A new and original pulse microwave-extraction procedure for AA extraction was also developed. Ascorbate from the plant extracts obtained was quantified and the linearity, precision, recovery, limit of detection (LOD) and limit of quantification (LOQ) were studied. LOD and LOQ were 0.2 and 0.22 mg/L for the established method, respectively. The mean recovery ranged from 90.7 to 102.3% with higher variation in the case of celery. Parsley contains the highest amount of ascorbic acid (264 mg AA/100 g of fresh plant), followed by dill (121 mg AA/100 g of fresh plant) and celery (103 mg AA/100 g of fresh plant).
      PubDate: 2014-10-01
       
  • Electrochemical studies on lawsone and its determination in henna (       class="a-plus-plus">Lawsonia inermis) extract
           using glassy carbon electrode
    • Abstract: Abstract The electrochemical behaviour of lawsone at glassy carbon electrode (GCE) was investigated by using cyclic and differential pulse anodic stripping voltammetric (DPASV) techniques. Cyclic voltammetry was used to study the influence of pH on the peak current and peak potential. The Mcllavnie’s buffer of pH 3.0 was selected as a suitable analytical medium in which lawsone exhibited sensitive diffusion controlled redox peaks (vs. Ag/AgCl). The peak current varied linearly with lawsone concentration in the range between 0.60 and 1.40 μM with a detection limit of 6 nM. The applicability of the proposed method was illustrated by the determination of lawsone present in real samples. A mean recovery of lawsone in the leaf of Lawsonia inermis was 99.5% with a relative standard deviation of 1.15%.
      PubDate: 2014-09-01
       
  • Rapid screening and determination of nerve agent metabolites in human
           urine by LC-MS/MS
    • Abstract: Abstract Qualitative screening procedures have been developed for the rapid detection and identification of the metabolites of nerve agents in the urine samples and extracts using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The combination of negative electrospray ionization (ESI) using a C18 column and water-methanol mobile phase modified with ammonium formate provides a rapid screening procedure for nerve agent degradation products with limit of detection of 1 ng/mL in the precursor-ion analysis. Also, determination of the alkyl methylphosphonic acids was carried out by the SRM scan mode with the limit of detection of 0.1 ng/mL. These procedures will be applicable to the trace analysis of metabolites of nerve agents in human urine matrices in the Organisation for the Prohibition of Chemical Weapons (OPCW) proficiency test.
      PubDate: 2014-09-01
       
  • Determination of cefazolin by oscillographic polarography as its        class="a-plus-plus">S,       class="a-plus-plus">S′-dioxide
    • Abstract: Abstract A simple rapid method is proposed to determine cefazolin in neat substances and powders for preparing injection solutions based on the preliminary oxidation of the preparation in weak acidic media by potassium peroxomonosulfate to respective S,S′-dioxide followed by its determination by oscillographic polarography. The concentration of the title material in the cefazolin substance was found to be 96.7%, RSD = 3%, δ= 2.4% and in the powder, 97.7%, RSD = 3%, δ = 2.3%.
      PubDate: 2014-09-01
       
  • Separation of vanadium(IV) from vanadium(V) and its determination in the
           presence of thiocyanate ions using two-phase aqueous systems
    • Abstract: Abstracts A two-phase system of polyethylene glycol PEG-1500 (C2H5OH, C3H7OH)-ammonium sulfate-water is proposed for the selective extraction and spectrometric determination of vanadium(IV) as its thiocyanate complex. The conditions of the separation of vanadium(IV) from vanadium(V) are optimized using polyethylene glycol or water soluble alcohols. The detection limit for vanadium(IV) in extractionatomic absorption determination is 2.8 μg/L and in combined photometric determination with chromazurol S, 10 μg/L. The methods are tested on mine, waste, and river waters. The relative standard deviation does not exceed 7%. The duration of analysis is 20 min.
      PubDate: 2014-09-01
       
  • The behavior of polyaniline-coated PVC membrane based on
           7,16-didecyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane for ph
           measurements in highly acidic media
    • Abstract: Abstract Polyaniline (PANI) chemically coated on polyvinylchloride (PVC) membrane based on a neutral carrier 7,16-didecyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (Kryptofix 22 DD) as the active component has been developed for determination of pH values ranging from pH 0.1–1. Effect of experimental parameters such as membrane composition, nature and amount of plasticizer, lipophilic additives and thickness of PANI film on the potential response of the pH electrode was investigated. The electrode has an apparent Nernstian response slope of 54.5 ± 0.4 mV/pH (at 20°C). The equilibrium water content of the electrode was determined in pure water and NaCl solution (I = 0.1 mol/kg). The electrode had low electric resistance, good potential stability and reproducibility (±1.5 mV, n = 10). It had a rapid potential response to changes of pH (15 s). The excellent performance in terms of linearity, stability and fast response makes this device suitable for pH measurements in highly acidic media.
      PubDate: 2014-09-01
       
 
 
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